The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effe...The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effect in the tunnel,and the influence of different design parameters on the smoke exhaust effect and temperature attenuation of the tunnel can help engineers in designing a more effective centralized smoke exhaust system for the tunnel.In this paper,the Fire Dynamic Simulator(FDS)is utilized to examine smoke exhaust vent settings for a centralized exhaust system in shield tunnel with both flat and sloped conditions,including slopes of+4.5%and−4.5%,under a 30MWfire power with a 150m^(3)/s smoke exhaust rate.The results suggest that maintaining a vent spacing of 60m and a vent size of 4.0 m×1.5 m is a reasonable configuration for centralized smoke exhaust systems in both flat and slope shield tunnels.This choice helpsminimize construction costs and prevent excessive smoke accumulation.It also promotes favorable conditions for maintaining temperature distribution at 2-m height,visibility,smoke spread distance,and temperature below the ceiling,all below the threshold values,while ensuring high smoke extraction efficiency.However,in the slope section,the chimney effect can disrupt exhaust efficiency,visibility,ceiling temperature,and temperature distribution at a height of 2 m.Employing different opening methods,such as having 2 vents up and 4 vents down in a+4.5%slope and 4 vents up and 2 vents down in a−4.5%slope,can help mitigate these effects.Furthermore,the temperature decay formula for shield tunnels follows a bi-exponential decay pattern,and different design parameters of centralized smoke exhaust systems have minimal effects on temperature decay in shield tunnels.展开更多
This study focused on increasing the efficiency of the smoke exhaust system of an extra-wide(eight-lane,dual-directional)immersed tunnel with a specific quantity of exhaust.The Shenzhen-Zhongshan immersed tunnel was s...This study focused on increasing the efficiency of the smoke exhaust system of an extra-wide(eight-lane,dual-directional)immersed tunnel with a specific quantity of exhaust.The Shenzhen-Zhongshan immersed tunnel was selected as the application example.A numerical simulation based on fire dynamics simulator was conducted.In the model,the concrete structure of the main body of the immersed tubes was not altered.The adoption of supplementary exhaust ducts increased the efficiency from 73%to 98%under the condition of no longitudinal wind.When a 50-MW fire occurred between two adjacent ducts,with a longitudinal wind velocity of 2 m/s,the efficiency reached 88%or more when the two ducts were opened.Furthermore,a safety evacuation path was developed.The results suggest that the addition of supplementary exhaust ducts combined with a rational longitudinal wind velocity is necessary for an extra-wide immersed tunnel.展开更多
This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under ...This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under different conditions,including variations in heat release rates,exhaust volumetric flow rates,spacing between smoke outlets,and the longitudinal fire source positions.Results indicate that altering the fire source positions and the smoke outlets in the tunnel leads to variations in the properties of smoke flow both the fire source upstream and downstream;the distance between fire source and smoke outlet increases gradually,airflow rate decreases initially and eventually reaches a stable state.Similarly,smoke mass flow rate exhibits an increasing trend that eventually reaches a stable state.Moreover,the heat exchange between the tunnel walls and hot smoke increases as the smoke outlet moves further away from the fire source.This interaction leads to a reduction in the heat exhaust coefficient and a decrease in the distance the smoke spreads.This study investigates the impact of altering the relative longitudinal fire source positions and smoke outlet on smoke flow characteristics by numerical simulation.A theoretical analytical method is used to give a predictive model for the heat exhaust coefficient and the smoke spreading distance.This research can support the theory and technical process of tunnel smoke exhaust prevention and control.展开更多
The Beijing Jingchu Industry General Co. is a famous enterprise producing kitchen utensils and household electrical appliances. The Jingchu brand energysaving oil and smoke exhauster produced by the company is made of...The Beijing Jingchu Industry General Co. is a famous enterprise producing kitchen utensils and household electrical appliances. The Jingchu brand energysaving oil and smoke exhauster produced by the company is made of imported materials with overseas advanced technology for production and measurement. All indexes have reached the domestic advanced level. The exhauster is equipped with展开更多
The atrium of public buildings is a large space that runs through from top to bottom and left to right in the building. The fire prevention problem is more complicated than that of ordinary buildings. If the atrium is...The atrium of public buildings is a large space that runs through from top to bottom and left to right in the building. The fire prevention problem is more complicated than that of ordinary buildings. If the atrium is not properly designed for fire prevention, it may lead to great disaster. The "Technical Standard for Smoke Control and Extraction Systems in Buildings" GB51251-2017 clearly stipulates the design and calculation of smoke extraction volume (natural smoke extraction and mechanical smoke extraction) in atriums. The design of smoke extraction in atriums of multi-storey public buildings is difficult to achieve regardless of natural smoke extraction or mechanical smoke extraction. Through specific cases, this paper analyzes how to carry out effective fire protection design in HVAC design, which can not only meet the requirements of fire protection regulations, but also not destroy the space feeling and visual aesthetic feeling of atrium.展开更多
In order to investigate the smoke diffusion law under the one-side centralized smoke exhaust mode of the urban connection tunnel (UTLT), the influence of the area of the smoke exhaust port on the smoke control, temper...In order to investigate the smoke diffusion law under the one-side centralized smoke exhaust mode of the urban connection tunnel (UTLT), the influence of the area of the smoke exhaust port on the smoke control, temperature distribution and smoke exhaust efficiency of the one-side centralized tunnel was experimentally studied. The results show that increasing the area of the smoke outlet will reduce the thickness of the smoke layer;The top smoke outlet can effectively reduce the temperature at the smoke outlet, and the temperature at the downstream of the smoke outlet is obviously lower than the temperature at the upstream of the smoke outlet;The bend in UTLT can delay the longitudinal spread of smoke. Changing the distance between the fire source and the smoke outlet has little effect on the one-sided centralized smoke exhaust.展开更多
In order to improve the maintenance efficiency,extend the use time,ensure that the exhaust emission meets the standard,forthe 830E truck heating bucket exhaust pipe design defects,the current single smoke exhaust syst...In order to improve the maintenance efficiency,extend the use time,ensure that the exhaust emission meets the standard,forthe 830E truck heating bucket exhaust pipe design defects,the current single smoke exhaust system is transformed into atime period,convertible smoke exhaust system.After the transformation,it can not only realize the side row to prevent direct corrosion of the box bucket in summer,but also realize the heating of the box bucket at low temperature in winter to prevent snow and ice and frozen blocks from sticking to the box bucket and the materials transported.After the transformation can save a lot of manpower,material resources,financial resources,improve the service life.展开更多
This paper investigated the smoke exhaustion characteristics and critical shaft height in a slope tunnel with naturally ventilated shafts based on reduced-scale tunnel experiments.The effects of longitudinal fire loca...This paper investigated the smoke exhaustion characteristics and critical shaft height in a slope tunnel with naturally ventilated shafts based on reduced-scale tunnel experiments.The effects of longitudinal fire location,shaft setting,heat release rate(HRR) and tunnel slope on smoke exhaustion were studied.Experimental results show that the slope has great effect on smoke exhaustion.Moreover,the critical shaft height for complete smoke exhaustion of slope tunnels was studied theoretically and experimentally.The research indicates that the critical shaft height exhibits no dependency on the HRR.Notably,with the increasing of shaft length,the critical shaft height firstly decreases and then remains stable until it finally decreases to zero.Simultaneously,the critical shaft height increases with the increase of the slope and the distance between the shaft and the fire source.In addition,a theoretical model for predicting the critical shaft height was established and verified.The research results can provide some reference for the design of natural ventilation smoke exhaustion with shafts in slope tunnels.展开更多
The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms,leading to persistent smoke accumulation in the launch area,which poses s...The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms,leading to persistent smoke accumulation in the launch area,which poses significant challenges for visibility control and target detection.However,existing Random Walk Model(RWM)typically rely on simplified assumptions such as free-space domains or regular boundary geometries,limiting their applicability to complex wall-constrained scenarios.To fill this gap,a Geometric Topology and Wall-Constrained Random Walk Model(GTWC-RWM)is developed to simulate particle transport in complex launch-site environments.The model incorporates wall effects—including reflection,slip,and adsorption—through ray–triangle intersection methods for collision detection.Collision response parameters are expressed as second-order polynomials of incidence angle and calibrated using experimental data to ensure physical consistency.Validation against reference data and geometric obstacle scenarios confirms the model's predictive capability,yielding a maximum relative error of less than 26.16%.Simulations reveal that wall-constrained effects significantly impede dispersion,with concentration gradients reaching up to 58.79%between obstructed and unobstructed regions.A sensitivity analysis quantifies the influence of key parameters on near-wall concentration distributions.展开更多
In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increa...In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increasing the open area of the window could effectively improve the overall smoke exhaust effect.When the top windows were open and the opening ratio increased from 19.2%to 24.3%,the optical density was decreased by 12.4%.The average smoke exhaust rate per unit area of the window did not change significantly.Increasing the area of the natural smoke exhaust window could effectively increase the smoke exhaust rate and improve the overall effect of smoke extraction.When the top windows were open,the temperature rise on the top floor was 30.8%-47.5%lower while the visibility was 16.8%-21.9%higher than that when the side windows were open.展开更多
文摘The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effect in the tunnel,and the influence of different design parameters on the smoke exhaust effect and temperature attenuation of the tunnel can help engineers in designing a more effective centralized smoke exhaust system for the tunnel.In this paper,the Fire Dynamic Simulator(FDS)is utilized to examine smoke exhaust vent settings for a centralized exhaust system in shield tunnel with both flat and sloped conditions,including slopes of+4.5%and−4.5%,under a 30MWfire power with a 150m^(3)/s smoke exhaust rate.The results suggest that maintaining a vent spacing of 60m and a vent size of 4.0 m×1.5 m is a reasonable configuration for centralized smoke exhaust systems in both flat and slope shield tunnels.This choice helpsminimize construction costs and prevent excessive smoke accumulation.It also promotes favorable conditions for maintaining temperature distribution at 2-m height,visibility,smoke spread distance,and temperature below the ceiling,all below the threshold values,while ensuring high smoke extraction efficiency.However,in the slope section,the chimney effect can disrupt exhaust efficiency,visibility,ceiling temperature,and temperature distribution at a height of 2 m.Employing different opening methods,such as having 2 vents up and 4 vents down in a+4.5%slope and 4 vents up and 2 vents down in a−4.5%slope,can help mitigate these effects.Furthermore,the temperature decay formula for shield tunnels follows a bi-exponential decay pattern,and different design parameters of centralized smoke exhaust systems have minimal effects on temperature decay in shield tunnels.
基金Project supported by the National Key R&D Program of China(No.2018YFC0808103)。
文摘This study focused on increasing the efficiency of the smoke exhaust system of an extra-wide(eight-lane,dual-directional)immersed tunnel with a specific quantity of exhaust.The Shenzhen-Zhongshan immersed tunnel was selected as the application example.A numerical simulation based on fire dynamics simulator was conducted.In the model,the concrete structure of the main body of the immersed tubes was not altered.The adoption of supplementary exhaust ducts increased the efficiency from 73%to 98%under the condition of no longitudinal wind.When a 50-MW fire occurred between two adjacent ducts,with a longitudinal wind velocity of 2 m/s,the efficiency reached 88%or more when the two ducts were opened.Furthermore,a safety evacuation path was developed.The results suggest that the addition of supplementary exhaust ducts combined with a rational longitudinal wind velocity is necessary for an extra-wide immersed tunnel.
文摘This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under different conditions,including variations in heat release rates,exhaust volumetric flow rates,spacing between smoke outlets,and the longitudinal fire source positions.Results indicate that altering the fire source positions and the smoke outlets in the tunnel leads to variations in the properties of smoke flow both the fire source upstream and downstream;the distance between fire source and smoke outlet increases gradually,airflow rate decreases initially and eventually reaches a stable state.Similarly,smoke mass flow rate exhibits an increasing trend that eventually reaches a stable state.Moreover,the heat exchange between the tunnel walls and hot smoke increases as the smoke outlet moves further away from the fire source.This interaction leads to a reduction in the heat exhaust coefficient and a decrease in the distance the smoke spreads.This study investigates the impact of altering the relative longitudinal fire source positions and smoke outlet on smoke flow characteristics by numerical simulation.A theoretical analytical method is used to give a predictive model for the heat exhaust coefficient and the smoke spreading distance.This research can support the theory and technical process of tunnel smoke exhaust prevention and control.
文摘The Beijing Jingchu Industry General Co. is a famous enterprise producing kitchen utensils and household electrical appliances. The Jingchu brand energysaving oil and smoke exhauster produced by the company is made of imported materials with overseas advanced technology for production and measurement. All indexes have reached the domestic advanced level. The exhauster is equipped with
文摘The atrium of public buildings is a large space that runs through from top to bottom and left to right in the building. The fire prevention problem is more complicated than that of ordinary buildings. If the atrium is not properly designed for fire prevention, it may lead to great disaster. The "Technical Standard for Smoke Control and Extraction Systems in Buildings" GB51251-2017 clearly stipulates the design and calculation of smoke extraction volume (natural smoke extraction and mechanical smoke extraction) in atriums. The design of smoke extraction in atriums of multi-storey public buildings is difficult to achieve regardless of natural smoke extraction or mechanical smoke extraction. Through specific cases, this paper analyzes how to carry out effective fire protection design in HVAC design, which can not only meet the requirements of fire protection regulations, but also not destroy the space feeling and visual aesthetic feeling of atrium.
文摘In order to investigate the smoke diffusion law under the one-side centralized smoke exhaust mode of the urban connection tunnel (UTLT), the influence of the area of the smoke exhaust port on the smoke control, temperature distribution and smoke exhaust efficiency of the one-side centralized tunnel was experimentally studied. The results show that increasing the area of the smoke outlet will reduce the thickness of the smoke layer;The top smoke outlet can effectively reduce the temperature at the smoke outlet, and the temperature at the downstream of the smoke outlet is obviously lower than the temperature at the upstream of the smoke outlet;The bend in UTLT can delay the longitudinal spread of smoke. Changing the distance between the fire source and the smoke outlet has little effect on the one-sided centralized smoke exhaust.
基金2022 Liaoning Natural Science Foundation Plan(Yingkou Joint Fund)Damping damping Design and Optimization of New Bore Head Transmission Structure(Fund No.:2022-YKLH-17)In 2023,the key scientific research project of Yingkou Institute of Technology is the Design and Optimization of Smoke Drainage Pipe for New Mining Truck(Fund No.:ZDIL202306)2021 Natural Science Foundation of Liaoning Province(Yingkou Joint Fund)Research on Dynamic Characteristics of Damped Dynamic Reduction Vertical Holack(Fund No.:2021-YKLH-08).
文摘In order to improve the maintenance efficiency,extend the use time,ensure that the exhaust emission meets the standard,forthe 830E truck heating bucket exhaust pipe design defects,the current single smoke exhaust system is transformed into atime period,convertible smoke exhaust system.After the transformation,it can not only realize the side row to prevent direct corrosion of the box bucket in summer,but also realize the heating of the box bucket at low temperature in winter to prevent snow and ice and frozen blocks from sticking to the box bucket and the materials transported.After the transformation can save a lot of manpower,material resources,financial resources,improve the service life.
基金financially supported by National Natural Science Foundation of China (Grant No.52038009)。
文摘This paper investigated the smoke exhaustion characteristics and critical shaft height in a slope tunnel with naturally ventilated shafts based on reduced-scale tunnel experiments.The effects of longitudinal fire location,shaft setting,heat release rate(HRR) and tunnel slope on smoke exhaustion were studied.Experimental results show that the slope has great effect on smoke exhaustion.Moreover,the critical shaft height for complete smoke exhaustion of slope tunnels was studied theoretically and experimentally.The research indicates that the critical shaft height exhibits no dependency on the HRR.Notably,with the increasing of shaft length,the critical shaft height firstly decreases and then remains stable until it finally decreases to zero.Simultaneously,the critical shaft height increases with the increase of the slope and the distance between the shaft and the fire source.In addition,a theoretical model for predicting the critical shaft height was established and verified.The research results can provide some reference for the design of natural ventilation smoke exhaustion with shafts in slope tunnels.
文摘The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms,leading to persistent smoke accumulation in the launch area,which poses significant challenges for visibility control and target detection.However,existing Random Walk Model(RWM)typically rely on simplified assumptions such as free-space domains or regular boundary geometries,limiting their applicability to complex wall-constrained scenarios.To fill this gap,a Geometric Topology and Wall-Constrained Random Walk Model(GTWC-RWM)is developed to simulate particle transport in complex launch-site environments.The model incorporates wall effects—including reflection,slip,and adsorption—through ray–triangle intersection methods for collision detection.Collision response parameters are expressed as second-order polynomials of incidence angle and calibrated using experimental data to ensure physical consistency.Validation against reference data and geometric obstacle scenarios confirms the model's predictive capability,yielding a maximum relative error of less than 26.16%.Simulations reveal that wall-constrained effects significantly impede dispersion,with concentration gradients reaching up to 58.79%between obstructed and unobstructed regions.A sensitivity analysis quantifies the influence of key parameters on near-wall concentration distributions.
基金This work was supported by SCFRI research project(No.T2019881101,No.T2019880402).
文摘In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increasing the open area of the window could effectively improve the overall smoke exhaust effect.When the top windows were open and the opening ratio increased from 19.2%to 24.3%,the optical density was decreased by 12.4%.The average smoke exhaust rate per unit area of the window did not change significantly.Increasing the area of the natural smoke exhaust window could effectively increase the smoke exhaust rate and improve the overall effect of smoke extraction.When the top windows were open,the temperature rise on the top floor was 30.8%-47.5%lower while the visibility was 16.8%-21.9%higher than that when the side windows were open.
